Ligaments are strong bands of tissue that hold bones together. In the elbow joint, the ulnar collateral ligament, or UCL, holds the ulna (lower arm bone) to the humerus (upper arm bone). When the ulnar collateral ligament gets torn due to injury, the elbow can become unstable.
The most common symptom of a torn ulnar collateral ligament elbow injury is pain on the medial side (inside, or pinky finger side) of the arm, from the elbow to the wrist. Occasionally, a baseball player who tears his UCL may feel a “pop” with intense pain after throwing.
The ulnar collateral ligament may become torn due to a single traumatic episode — or more commonly, repetitive injury, such as throwing a baseball. The UCL may also become torn due to trauma, such as a broken elbow.
A torn ulnar collateral ligament is diagnosed by physical examination. An X-ray or MRI scan may be required to confirm diagnosis.